Showed Maximum Activity Research Articles

Imine-functionalized organotin(IV) carboxylates: Syntheses, structures and antibacterial activities

Six new imine-functionalized organotin(IV) carboxylates viz. {[(n-Bu)2Sn(L1)]2O]}2 (1), [(t-Bu)2Sn(L1)2] (2), [Ph3Sn(L1)] (3), [(t-Bu)4Sn2(OH)2(L2)2] (4), [Ph3Sn(L2)] (5) and [(t-Bu)2Sn(L3)2] (6) have been synthesized and characterized by FT-IR spectroscopy, elemental analysis, 1H, 13C{1H} and 119Sn{1H} NMR spectroscopy. The solid-state molecular structures of all compounds have been elucidated by single-crystal X-ray diffraction analyses. Compound 1 shows a ladder-type structure consisting of four tin atoms. Compounds 2–3 and 5–6 are mononuclear and contain only one tin atom in each compound. Interestingly, compound 4 exhibits a hydroxide-bridged dinuclear structure. All compounds were evaluated for their antibacterial activities against E. coli XL-1 Blue cells, and compound 1 showed maximum activity amongst all compounds.

Novel alkaline protease of <em>Staphylococcus cohnii </em>N3 isolated from poultry farm soil used for silver recovery from waste X-ray film

Alkaline proteases are one of the most widely used as industrial enzyme recently explored for its effective degrading ability in bioremediation. In the present study alkaline protease producing bacteria was isolated from soil samples collected from waste dumped area in poultry farm. The isolate was identified as Staphylococcus cohnii N3 strain by 16s rRNA sequencing analysis. The effect of pH and temperature on alkaline protease was found that showed maximum activity at pH 9 and at temperature 60 (162.U/ml). The isolated S. cohnii N3 was further experimented for silver recovery and gelatin hydrolysis. Gelatin hydrolysis was monitored by measuring increase in turbidity in the hydrolysate. Gelatin layer was stripped completely within 20 min at 40 ˚C, pH 9. Rate of gelatin hydrolysis increased with increased in time shows complete decolorization of X-ray film proves its suitability for silver recovery.

Role of different oxidation states of Crn+-TiO2 nanocomposites for the degradation of drugs under solar irradiation

The present work focuses on the effect of different oxidation states of impregnated Crn + ionic species over TiO2 surface. The resulting Crn + -TiO2 nanocomposites have been revealed to have improved optical response, charge carrier relaxation dynamics, adsorption and photocatalytic behaviour which is correlated to variable oxidation states of these composite materials. The optical absorption spectra (400–500 nm and 583–800 nm) covered the entire visible region after Crn + incorporation to have maximum photoresponse. These bands have been assigned to the 4A2g → 4T1g and 4A2g → 4T2g transitions, respectively. A remarkable quenching of photoluminescence peaks and further successive enhanced carrier relaxations from 3.62 ns (bare TiO2) to 3.73 and 4.09 ns for Cr3+ and Cr6+ loaded TiO2 catalysts were observed. The XPS analysis confirmed the presence of Cr3+ and Cr6+ oxidation states while a reduction in particle sizes with increased oxidation state (Cr3+; 16.9 nm and Cr6+; 8.6 nm) was witnessed by HRTEM images. The electrokinetic parameters such as surface charge demand, zeta and streaming potentials were also found to vary as a function of the oxidation state of the nanocatalysts. These Crn + -TiO2 catalysts were then analyzed for the photooxidation of aspirin and paracetamol drugs with some interesting behaviour. For aspirin, Cr6+-TiO2 with rate constant, k = 18.815 × 10−3 min−1 while in case of paracetamol, Cr3+-TiO2 catalyst with k = 8.052 × 10−1 h−1 showed maximum activity under solar irradiation. The observed photoactivity has been correlated to the different chemical nature of substrate molecules, catalyst oxidation state effects and catalyst-substrate associations.

Synthesis and Antibacterial, Antioxidant, and Molecular Docking Analysis of Some Novel Quinoline Derivatives

2-Chloroquinoline-3-carbaldehyde and 2-chloro-8-methylquinoline-3-carbaldehyde derivatives were synthesized through Vilsmeier formulation of acetanilide and N-(o-tolyl)acetamide. Aromatic nucleophilic substitution reaction was used to introduce various nucleophiles in place of chlorine under different reaction conditions. The carbaldehyde group was oxidized by permanganate method and reduced with metallic sodium in methanol and ethanol. The synthesized compounds were characterized by UV-Vis, IR, and NMR. The antibacterial activity of the synthesized compounds was screened against two Gram-positive bacteria (Bacillus subtilisATCC6633 andStaphylococcus aureusATCC25923) and two Gram-negative bacteria (Escherichia coliATCC 25922 andPseudomonas aeruginosaATCC 27853). Most of the compounds displayed potent activity against two or more bacterial strains. Among them, compounds6and15showed maximum activity againstPseudomonas aeruginosawith mean inhibition zones of 9.67 ± 1.11 and 10.00 ± 0.44 mm, respectively, while ciprofloxacin showed mean inhibition zone of 8.33 ± 0.44 mm at similar concentration. On the other hand, compound8exhibited maximum activity againstEscherichia coliwith inhibition zones of about 9.00 ± 0.55 mm at 300 μg/mL and 11.33 ± 1.11 mm at 500 μg/mL. The radical scavenging activity of these compounds was evaluated using 1,1-diphenyl-2-picryl hydrazyl (DPPH), and all of them displayed moderate antioxidant activity, with compound7exhibiting the strongest activity. The molecular docking study of the synthesized compounds was conducted to investigate their binding pattern with DNA gyrase, all of them were found to have minimum binding energy ranging from –6.0 to –7.33 kcal/mol, and the best result was achieved with compound11. The findings of the in vitro antibacterial and molecular docking analysis demonstrated that the synthesized compounds have potential of antibacterial activity and can be further optimized to serve as lead compounds.

Production, optimization and partial purification of l-asparaginase from endophytic fungus Aspergillus sp., Isolated from Cassia fistula

Endophytes are relatively less studied microbes which in future may serve as potential sources of novel secondary metabolites for use in medical, agricultural and pharmaceutical industries. In present study six fungal endophytes were isolated from the leaves, stem and fruit of Cassia fistula and screened for asparaginase production on modified Czapek Dox agar supplemented with L-asparagine as a substrate and phenol red as indicator. L-asparaginase production by Aspergillus sp. using variable carbon and nitrogen sources, temperature and pH revealed maximum asparaginase production with xylose as carbon source and ammonium nitrate as nitrogen sources at pH 6.0 with incubation temperature of 30°C. The disc size optimization for enzyme revealed maximum activity with 10 mm size disc (0.22 IU mg−1 enzyme activity). The endophyte studied showed maximum activity under stationary condition (2.7 IU mg−1) than under shaking condition. Various purification steps included salt precipitation, dialysis, followed by separation on Sephadex G-100 gel filtration. The partially purified enzyme showed the activity of 4.9 IU mg−1. It may be concluded that the isolated Aspergillus sp. may serve as a vital source of L-asparaginase for future use.

Enzyme Inhibitory, Antioxidant And Antibacterial Potentials Of Synthetic Symmetrical And Unsymmetrical Thioureas.

BackgroundIn this study, 2 symmetrical and 3 unsymmetrical thioureas were synthesized to evaluate their antioxidant, antibacterial, antidiabetic, and anticholinesterase potentials.MethodsThe symmetrical thioureas were synthesized in aqueous media in the presence of sunlight, using amines and CS2 as starting material. The unsymmetrical thioureas were synthesized using amines as a nucleophile to attack the phenyl isothiocyanate (electrophile). The structures of synthesized compounds were confirmed through H1 NMR. The antioxidant potential was determined using DPPH and ABTS assays. The inhibition of glucose-6-phosphatase, alpha amylase, and alpha glucosidase by synthesized compounds was used as an indication of antidiabetic potential. Anticholinesterase potential was determined from the inhibition of acetylcholinesterase and butyrylcholinesterase by the synthesized compounds.ResultsThe highest inhibition of glucose-6-phosphatase was shown by compound V (03.12 mg of phosphate released). Alpha amylase was most potently inhibited by compound IV with IC50 value of 62 µg/mL while alpha glucosidase by compound III with IC50 value of 75 µg/mL. The enzymes, acetylcholinesterase, and butyrylcholinesterase were potently inhibited by compound III with IC50 of 63 µg/mL and 80 µg/mL respectively. Against DPPH free radical, compound IV was more potent (IC50 = 64 µg/mL) while ABTS was more potently scavenged by compound I with IC50 of 66 µg/mL. The antibacterial spectrum of synthesized compounds was determined against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Agrobacterium tumefaction and Proteus vulgaris). Compound I and compound II showed maximum activity against A. tumefaction with MIC values of 4.02 and 4.04 µg/mL respectively. Against P. vulgaris, compound V was more active (MIC = 8.94 µg/mL) while against S. aureus, compound IV was more potent with MIC of 4.03 µg/mL.ConclusionFrom the results, it was concluded that these compounds could be used as antibacterial, antioxidant, and antidiabetic agents. However, further in vivo studies are needed to determine the toxicological effect of these compounds in living bodies. The compounds also have potential to treat neurodegenerative diseases.

Molecular Cloning, Expression and Biochemical Characterization of a Family 5 Glycoside Hydrolase First Endo-Mannanase (RfGH5_7) from Ruminococcus flavefaciens FD-1 v3.

The cellulosomal enzyme, RfGH51/2, of Ruminococcus flavefaciens contains an N-terminal module, a family 5 glycoside hydrolase GH5_4 with a putative endoglucanase activity, while C-terminal domain is a putative endo-mannanase (GH5_7). The two putative catalytic modules are separated by family 80 carbohydrate binding module (CBM80) having wide ligand specificity. The putative endo-mannanase module, GH5_7 (RfGH5_7), was cloned, expressed in Escherichia coli BL-21(DE3) cells and purified. SDS-PAGE analysis of purified RfGH5_7 showed molecular size ~ 35kDa. Substrate specificity analysis of RfGH5_7 showed maximum activity against locust bean galactomannan (298.5 U/mg) followed by konjac glucomannan (256.2 U/mg) and carob galactomannan (177.2 U/mg). RfGH5_7 showed maximum activity at optimum pH 6.0 and temperature 60°C. RfGH5_7 displayed stability in between pH 6.0 and 9.0 and thermostability till 50°C. 10mM Ca2+ ions increased the enzyme activity by 33%. The melting temperature of RfGH5_7 was 84°C that was not affected by Ca2+ ions or chelating agents. RfGH5_7 showed, Vmax, 389 U/mg and Km, 0.92mg/mL for locust bean galactomannan. TLC analysis revealed that RfGH5_7 hydrolysed locust bean galactomannan predominantly to mannose, mannobiose, mannotriose and higher degree of polymerization of manno-oligosaccharides indicating an endo-acting catalytic mechanism. This study revealed a highly active and thermostable endo-mannanase with considerable biotechnological potential.

Exploitation and characterization of three versatile amidase super family members from Delftia tsuruhatensis ZJB-05174

Amidases can be assigned into two families according to their amino acid sequences. Three amidases (Dt-Amis) were mined and identified from genome of Delftia tsuruhatensis. Homology analysis demonstrated that Dt-Ami 2 and Dt-Ami 6 belonged to amidase signature (AS) family, while Dt-Ami 7 belonged to nitrilase superfamily. AS amidases were shown to hydrolyze a wide spectrum of amides. Kinetic analysis demonstrated that the extension of chain length of aliphatic amides considerably decreased the Km values, and the turnover numbers (kcat) were high with linear aliphatic amides as substrates. Dt-Ami 2 showed maximum activity near a quite alkaline pH (11.0) and exhibited opposite enantioselectivity to Dt-Ami 6. Furthermore, a novel bioprocess for hydrolysis of 1-cyanocyclohexaneacetamide was developed using Dt-Ami 6 as biocatalyst, resulting in >99% conversion within 1.5h at a substrate loading of 100g/L by 0.5g/L of Escherichia coli cells. On the other hand, nitrilase superfamily amidase only hydrolyzed aliphatic amides. The Km values of Dt-Ami 7 were considerably increased with the extension of chain length of aliphatic amides. The characterized enzymes from different families showed distinct biochemical characteristics and catalytic properties, leading to a better understanding of the two super amidase family members.

Assessment of Antimicrobial Activity of Actinobacteria Inhabiting Harsh Conditions

In this study, 63 isolates of actinobacteria were isolated from marine sediment and sandy soil of Saint Katherine, Egypt and examined for antimicrobial activity. Both sites were highly inhabited by rare promising Actinobacteria species. Recovered Actinobacteria belonging to genus Streptomyces, Actinomadura, Micromonospora, Microtetraspora, Nocardia, Pseudonocardia Nocardiopsis, Actinoplanes, Pilimelia and Spirellospora. Their extracts exhibited wide antimicrobial activities towards 4 clinical pathogens. Out of them 49.21% showed potent inhibitory effect against test pathogens in primary and secondary screening methods in which genus Actinomadura was significantly the highest followed by genus Streptomyces then genus Micromonospora. The crude extracts showed 0.3-20 mm inhibition zone in disc diffusion method against tested pathogens. The active compounds were purified by preparative TLC, which showed retention factor value (RF) of 0.14-0.857 with isolated bioactive Actinobacteria and identified using different reference antibiotics. In bioautography, TLC spot of Actinomadura roseoviolacea with RF of 0.26 showed maximum activity with 40 mm inhibition zone and nearby Tetracycline reference antibiotic. This isolate show safe hemolytic activity In vitro analysis.

Nocardiopsis sp. 5 Endophytic to Tulsi Leaves – Isolation and Antimicrobial Activity

Aims: To isolate and identify the endophytic Nocardiopsis sp.5 from Tulsi (Ocimum sanctum) leaves and estimates its antimicrobial activity against various human pathogens and tea pathogens. Study Design: Rare endophytic actinobacteria isolation, identification and estimation of antimicrobial activity. Place and Duration of Study: Department of Botany and Department of Bioinformatics, Nirmala College for Women, Coimbatore – between December 2011 and December 2012. Methodology: Pre-sterilization of Ocimum sanctum leaves and isolation of rare endophytic actinomycetes using selective media. Estimation of antimicrobial activity of these isolates by primary and secondary streaking methods. Morphological and Molecular Identification of the most bioactive isolate. Results: Out of 11 endophytes, four isolates (2, 3, 5, and 9) showed antagonistic activity against tea and human pathogens. Among these four isolates, isolate no.5 showed maximum activity against all the human pathogenic microorganisms such as Staphylococcus aureus (21mm), Candida albicans (18 mm), Enterococcus faecalis (19mm), Vibrio cholera (18mm) and tea pathogens such as Glomerella cingulata (14mm) Hypoxylon serpens (17mm) and Pestalopsis theae (18mm). Hence, morphological and phylogenetic studies show that isolate no.5 belongs to Nocardiopsis group, showing 99% similarity to both Nocardiopsis synnemataformans and Nocardiopsis dassonvillei. Conclusion: Endophytic Nocardiopsis strain 5 was shown to produce good antimicrobial activity Short Communication Singh and Padmavathy; BMRJ, 5(3): 194-202, 2015; Article no.BMRJ.2015.021 195 against plant pathogens and human pathogens. Further purification, structure elucidation and characterization of the antimicrobial compound from Nocardiopsis 5 strain are recommended. There is definite scope for bioprospecting of antagonistic actinomycetes from Western Ghats once appropriate consistent studies are undertaken.

Synthesis and biological evaluation of some 4-(6-substituted-1,3-benzothiazol-2-yl)amino-1,3-thiazole-2-amines and their Schiff bases

With the aim of obtaining newer biologically active compounds, a series of 4-(6-substituted-1,3-benzothiazol-2-yl)amino-1,3-thiazole-2-amines (9–12) and 4-(6-substituted-1,3-benzothiazol-2-yl)amino-2-(4-substitutedphenyl-methylidene)amino-1,3-thiazole (13–28) were synthesized. The structures of all the synthesized compounds were confirmed by spectral (FTIR, 1H NMR and EI-MS) data and elemental (C, H, N) analysis. Furthermore, compounds (9–12) and (13–28) were screened for antibacterial, antifungal and anthelmintic activities. Almost all of these compounds showed moderate to excellent antimicrobial activity against two gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa), two gram positive bacteria (Staphylococcus aureus, Bacillus subtilis), pathogenic fungal strains (Candida albicans, Aspergillus niger) and good anthelmintic activity against earthworm species (Pontoscotex corethruses). Among the compounds tested, compounds 23 and 24 showed maximum activity against Gram negative and Gram positive bacteria, respectively. Compound 22 exhibited good antifungal activity while compound 26 displayed maximum anthelmintic activity comparable to the standard drugs.

MOLECULAR CHARACTERIZATION OF SECONDARY METABOLITE PRODUCING STREPTOMYCES SPECIES.

Actinomycetes are most prolific source of antibiotics. Present study was carried out to isolate Actinomycetes of antagonistic nature. In the present study soil samples were collected from different areas of Western Rajasthan. 10 isolates of Actinomycetes were isolated on Actinomycetes Isolation Agar (AIA). Several biochemical and physiological tests were performed for identification of these isolates. These Streptomyces isolates were screened for antagonistic potentiality against gram-positive and gram negative clinical isolates of human pathogenic bacteria. Isolates were cultivated in fermentation media for 7 days to extract out secondary metabolites or antibiotics of antimicrobial nature. Solvent extraction method was used to purifying antimicrobial compounds from filtrate. Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, Salmonella typhi and Pseudomonas aeruginosa were used as test pathogen. Only isolate no. 3 and 4 was found to be effective against most of the pathogens. Maximum activity of isolate no. 3 was recorded against Klebsiella pneumonia , minimum activity against Salmonella typhi and no activity was recorded against Pseudomonas aeruginosa. Whereas isolate no. 4 showed maximum activity against Staphylococcus aureus and minimum against Salmonella typhi and chloramphenicol was used as positive control. 16S rRNA sequencing of isolate no.3 and 4 had been done and isolate no. 3 shows 99% similarity with Streptomyces thermoliliacinus and isolate no. 4 shows 100% similarity with Streptomyces werrensis. Sequences obtained from 16S rRNA sequencing were submitted in NCBI data base. From all the results we concluded that Streptomyces isolates showed significant antagonism against test pathogens and reported first time from Western Rajasthan. Key words - Streptomyces , antagonism, fermentation process.

Synthesis of some novel pyrazolo[3,4- b]pyridine and pyrazolo[3,4- d]pyrimidine derivatives bearing 5,6-diphenyl-1,2,4-triazine moiety as potential antimicrobial agents

The reaction of 5,6-diphenyl-3-hydrazino-1,2,4-triazine ( 1) with bis(methylthio)methylene]malononitrile ( 2) afforded 5-amino-1-(5,6-diphenyl-1,2,4-triazin-3-yl)-3-(methylthio)-1 H-pyrazole-4-carbonitrile ( 3). Compound 3 reacted with thiourea to give 3,4-diaminopyrazolo[3,4- d]pyrimidine 5, which was treated with benzoyl chloride to give pyrazolo[5,4,3- kl]pyrimido[4,3- d]pyrimidine 6. Treatment of 3 with acetic anhydride produced 3-methylthio-pyrazolo[3,4- d]pyrimidine derivative 7, which was allowed to react with hydrazine hydrate to give the corresponding hydrazino derivative 8. Heterocyclization of 8 with benzoyl chloride and sodium pyruvate afforded the polyfused heterocycles 9 and 10, respectively. Reaction of 3 with benzoylacetone yielded pyrazolo[3,4- b]pyridine 12, which was allowed to react with malononitrile and acetanilide to get heterocyclic systems 13 and 14, respectively. Interaction of 3 with cyanoacetone gave pyrazolo[3,4- b]pyridine 15, which was refluxed in formic acid to yield pyrazolo[4′,3′:5,6]pyrido[4,3- d]pyrimidine 16. Reaction of 3 with 2 afforded the triazinylpyrazole derivative 17, which was reacted with hydrazine hydrate to give dipyrazolo[1,5-a:3′,4′- d]pyrimidine 19. Furthermore, treatment of the latter compound with methyl anthranilate furnished tetraheterocyclic compound 21. Structures of the products have been determined by elemental analysis and spectral studies. All compounds have been screened for their antibacterial and antifungal activities. Compounds 9, 10, 13, 19 and 21 showed maximum activity comparable to the standard drugs with lower toxicity in the case of 9 and 10.

Liquid phase hydroxylation of benzene over Cu-containing ternary hydrotalcites

One step liquid phase hydroxylation of benzene to phenol over ternary hydrotalcites of general formula CuM(II)M(III)–HT, where M(II) = Mg, Co, Ni and Zn and M(III) = Al, Fe and Cr was carried out in the temperature range 30–80 °C using pyridine as solvent and H 2O 2 as oxidant. Influence of various reaction parameters, such as reaction temperature, substrate:catalyst ratio, substrate weight, volume of the solvent, calcination temperature and reaction time were studied. Among the catalysts screened, CuCoAl–HT and CuNiAl–HT with (Cu + Co(or Ni))/Al = 3.0 and Cu/Co(or Ni) = 3.0 showed maximum activity with nearly 100% selectivity of phenol. The hydroxyl radical generated upon interaction of catalyst with oxidant is believed to be the active species involved in this reaction.

Lipase from a Brazilian strain of Penicillium citrinum.

A lipases (glycerol ester hydrolases E. C. 3.1.1.3) from a brazilian strain of Penicillium citrinum has been investigated. When the microorganism was cultured in the simple medium (1.0% olive oil and 0.5% yeast extract), using olive oil in as carbon source in the inocula, the enzyme extracted showed maximum activity (409 IU/mL). In addition, decrease of yeast extract concentration also reduces the lipase activity. Nevertheless, when yeast extract was replaced by ammonium sulfate, no activity was detected. Purification by precipitation with ammonium sulfate showed best activity in the 40-60% fraction. The optimum temperature for enzyme activity was found in the range of 34-37 degrees C. However, after 30 min at 60 degrees C, the enzyme was completely inactivated. The enzyme showed optimum at pH 8.0. The dried concentrated fraction (after dialysis and lyophilization) maintained its lipase activity at room temperature (28 degrees C) for 8 mo. This result in lipase stability suggests an application of lipases from P. citrinum in detergents and other products that require a high stability at room temperature.

Enzymes of carnitine acylation. Is overt carnitine palmitoyltransferase of liver peroxisomal carnitine octanoyltransferase?

Liver mitochondria prepared by differential centrifugation are contaminated by significant quantities of peroxisomes and microsomal fractions. 'Easily solubilized carnitine palmitoyltransferase' prepared from liver mitochondria is thought to originate from the outer surface of the mitochondrial inner membrane. We have characterized the carnitine palmitoyltransferase activities of freeze-thaw extracts of rat liver mitochondrial preparations. Chromatography on Sephadex G-100 yields two broad peaks of carnitine decanoyltransferase activity: one eluted at the end of the void volume, which can be removed (precipitated) by ultracentrifugation; the second peak represents the soluble activity and is eluted at an Mr near 70,000. The activity in the soluble peak is precipitated by an antibody raised against carnitine octanoyltransferase purified from mouse liver peroxisomes. In contrast, antibody raised against carnitine palmitoyltransferase purified from liver mitochondrial membranes had no effect (P. Brady & L. Brady, personal communication). The carnitine acyltransferase activities of the Mr-70,000 peak in the presence or absence of Tween 20 showed maximum activity with decanoyl-CoA and about one-third of this activity with palmitoyl-CoA, similar to peroxisomal carnitine octanoyltransferase. These data show that 7500 g preparations of liver mitochondria isolated by differential centrifugation are enriched by peroxisomal carnitine octanoyltransferase (approx. 20% of the protein of the fraction is peroxisomal) and indicate that this enzyme may be the one reported as 'overt' or 'easily solubilized' mitochondrial carnitine palmitoyltransferase.

The effect of pH on yields of hydroxyl radicals produced from superoxide by potential biological iron chelators

The efficiency of conversion of superoxide to hydroxyl radicals was measured by determining the yields of fluorescent hydroxybenzoates. A variety of iron-containing catalysts were tested. Citrate was the only organic salt which showed catalytic activity at neutral pH. Adenine nucleotides had little or no activity under similar conditions. Heme proteins were inactive and any catalytic activity measured with transferrin, lactoferrin, and conalbumin could be explained by free Fe 3+ released by the former two at acid pH. Many of the potential catalysts tested showed maximum activity near pH 4.8, where the rate of dismutation of O ⨪ 2 is highest. This suggests that in most systems the ratecontrolling step in the superoxide-driven Fenton process was the formation of H 2O 2. It was concluded that, with the exception of citrate, none of the biological compounds tested were able to assist the conversion of O ⨪ 2 to HO. with significant efficiency at neutral pH in homogeneous solutions.

Mikrobielle Entschwefelung von Erdöl und schweren Erdölfraktionen 5. Mitteilung: Anaerobe Entschwefelung von Romaschkino-Erdöl

Summary Basing on our investigations of anaerobic degradation of organic sulphur compounds, the anaerobic desulphurization of Romashkino petroleum is discussed in this paper. The influence of the pH. value and of the redox conditions is reported as well as the ratio petroleum/culture medium with regard to the efficiency of degradation. Four active mixed cultures from different sediments were isolated (GW 1–4), of which culture GW 1 showed maximum activity. Main component of these mixed cultures were Desulfovibrio species. Concomitant germs were found to be micrococci, bacilli, and Clostridia. Under conditions of continuous fermentation, the cultures GW 1 and GW 2 were able to desulphurize Romashkino petroleum up to 40 per cent. The sojourn time was in the range of 2 to 3 days. The desulphurization reaction was accompanied with degradation of hydrocarbons of the petroleum.

Isolation and characterization of heat stable proteinases from Pseudomonas isolate AFT 21.

Pseudomonas strain AFT 21 produced three heat stable extracellular proteinases in milk and nutrient broth at 7 or 21 degrees C, but the proportions depended on medium and cultivation temperature. The three proteinases were EDTA- and o-phenanthroline-sensitive metalloenzymes and were not inhibited by N-ethylmaleimide or phosphoramidon. Proteinases I and II showed maximum activity at pH 7-7.5 and proteinase III at pH 8.5. All three enzymes showed maximum activity at 45-47.5 degrees C, but had relatively high (19-27% of maximum) activity at 4 degrees C. They were unstable at 55 degrees C in phosphate buffer, pH 6.6, or synthetic milk ultrafiltrate (SMUF) containing 12 mmol Ca2+, but were stabilized by short preheating at 100 degrees C. They were extremely heat stable in both phosphate buffer and SMUF, pH 6.6, at 70-150 degrees C. Their D-values at 140 degrees C were 69, 54 and 80 s respectively. The Z-values for Pseudomonas AFT 21 proteinase III in phosphate buffer and SMUF were 29.7 and 30.3 degrees C respectively; the corresponding activation energies for inactivation were 8.7 x 10(4) J mol-1 and 9.2 X 10(4) J mol-1.

Lipoxygenase from baker's yeast: Purification and properties

1. 1. Lipoxygenase activity was extracted from the mitochondrial fraction of baker's yeast and was purified by affinity chromatography on a linoleyl aminoethyl sepharose column. Two lipoxygenases were eluted from the affinity column. 2. 2. The second enzyme eluted was characterized as a true lipoxygenase. 3. 3. The lipoxygenase eluted showed maximum activity at pH 6.5 with a K m of 2.68 × 10 −4 M on linoleate. 4. 4. The reaction products of the second lipoxygenase with linoleate were characterized by u.v., i.r., NMR spectra and mass spectrometry and were found to be: 9-hydroperoxy-octadeca- trans-10, cis-12-dienoic acid and 13-hydroperoxy-octadeca- cis-9, trans-11-dienoic acid.